Dietary exposures are believed to contribute to the majority of human cancers although most of the specific causal factors have not yet been identified. Since diet is a universal and modifiable exposure, research in this area offers the opportunity of significantly reducing cancer incidence and mortality. The Nutritional Epidemiology Branch conducts independent and collaborative research on the role of diet and nutritional status in cancer etiology. The Branch seeks to generate and test specific nutritional hypotheses, providing a scientific basis for public health recommendations and further understanding of the molecular basis of carcinogenesis. Investigations focus on dietary patterns, food groups, non-nutrient food constituents, and food preparation, as well as macronutrients and micronutrients. Our interests and expertise are broader than diet and nutrition, encompassing, for example, anthropometry, alcohol use, micronutrient and dietary supplements, physical activity, and endogenous hormones and growth factors. Because of the extensive biological research underlying contemporary nutrition, we frequently develop multidisciplinary studies with metabolic and/or molecular components. Currently, major research efforts are focused on 1) the influence of diet, early-life exposures, alcohol, body shape and size, endogenous hormones, and lifestyle on female tumors; 2) vegetables and fruits, micronutrients, carotenoids, and phytochemicals; 3) cooking-associated carcinogens, particularly heterocyclic aromatic amines; and 4) gene-nutrition interactions with particular attention to alcohol, folate, obesity, vegetables/fruits, and cooking mutagens. The role of nutrition is currently being evaluated in studies of lung, oral/pharyngeal, esophageal, stomach, colorectal, breast, endometrial, cervical, prostate, and brain cancers, as well as non-Hodgkin's lymphoma and malignant melanoma. Research approaches include descriptive analyses to generate hypotheses, analytic cohort and case-control investigations, larg-scale nutritional intervention studies (clinical trials), metabolic studies, and biologic marker and genetic susceptibility projects. Since variability in exposure facilitates and strengthens dietary studies, we will continue to engage in investigations utilizing migrant populations and international differences. We are also involved in developing and testing methods for nutritional epidemiology, including dietary questionnaires, biochemical assays, analytic approaches, and molecular probes of mechanisms. We have recently initiated a series of clinical and statistical studies to characterize dietary measurement error and refine relative risk de-attenuation techniques.